The invention relates to a multipurpose heating device designed to stand as a means for vaporising active substances, such as those used as insecticides or air-fresheners. The device, which is provided with a resistor, preferably of the PTC type, as the heating means, is structured to be able to evaporate liquids, tablets and gels without distinction, and at all times with a maximum performance, whatever the type of product to be evaporated may be.
There are electrically powered heating devices for vaporising liquids contained in diffusers, in some cases, and solids in the form of tablets in other cases, and indeed sometimes allowing tablets or liquids to be used without distinction, at will.
Present-day known devices for vaporising these products usually consist of a resistor which upon being activated heats a ceramic plate through which the relevant substance is vaporised close to a tablet diffuser. On the other hand, the heating device may be provided with a hole in which a wick is arranged projecting to the outside of a diffuser container holding a liquid product, thereby for heating of that wick to cause the liquid substance held in the container to be vaporised.
The power required in heating the heating device differs in the case of diffusers containing liquids and solid or tablet products, because in the first case a greater temperature is required at the mouth of the hole, whereas in the latter case the entire surface of the tablet can come into contact with the ceramic plate, whence less heat is required for sublimation to take place.
That is why a same heating device is neither advisable nor indeed effective to be able to vaporise tablet form products and vaporise liquid products without distinction, because the optimum working temperature of the wick in the case of liquid products does not match that of the tablet in the case of solid products, and therefore two types of heating devices are normally marketed, one specific for liquids and another one which is also specific for solids or tablets.
The heating device disclosed herein has been devised to fully overcome the above-mentioned drawbacks, i.e. it may be used without distinction and as may be required on case by case basis for liquid products or for tablet form products.
More specifically, the first novel characteristic of the heating device subject of the invention lies in that the general body of the heating device is supplemented with a spacer element provided with fixing means to the general body of the heating device, and therefore such spacer element may in each case be arranged at a greater or lesser distance from the heat radiating plate, thus allowing the solid product to be spaced to a greater or lesser extent; i.e. said spacer element is used to adjust the spacing between the tablet and the radiating plate in order to achieve an effective operation, starting from the fact that the heating device has previously been studied and constructed with a specific extent of evaporation and temperature to work as a heating device for liquid products, i.e. to work with a wick, and therefore taking that as the starting point, when the heating device is to be used to vaporise solid products, such as tablets, the spacer element will be used to adjust the spacing between the tablet and the radiating plate.
Another novel characteristic lies in that the heating plate at issue is not made of ceramics as is conventionally the case but consists of an aluminium plate. for an enhanced distribution of the temperature on the heater surface. and with that improvement the highest temperature reached on the surface of the aluminium radiating plate is less than in a ceramic heating device, thereby producing a lesser degradation of the insecticide active principles and of perfumes, due to an excess temperature, or in other words a better efficiency is achieved.
Another advantage of the inventive device lies in the perfect adjustment of the temperature required for each application, whether for liquid products or for tablets, based upon the above-mentioned spacer element.